How about trying a product called "soft paws". They are basically little plastic nail caps that come in different sizes (and fun colors) that you glue onto their nails. They are humane and don't bother the cat (although some cats don't like being held and having them applied). They last a month or two but fall off one by one as they shed the outside layer of their claws. Once they start to fall off a quick check every day or so to see if any need to be replaced is a good idea. It's basically a humane way of declawing. I am personally against declawing, but this is one instance where I might think it was ok (have to think about that one) since this cat doesn't seem like it has any other alternatives other than you making it work in your home.
They also look punk rock!